chasefleming/elem-go

Type-safe Go library for creating and manipulating HTML elements (with htmx helpers).

elem is a lightweight Go library for creating HTML elements programmatically. Utilizing the strong typing features of Go, elem ensures type safety in defining and manipulating HTML elements, minimizing potential runtime errors. It simplifies the generation of HTML views by providing a simple and intuitive way to create elements and set their attributes, properties, and content.

Features

• Easily create HTML elements with Go code.
• Type-safe definition and manipulation of elements, attributes, and properties.
• Supports common HTML elements and attributes.
• Utilities for simplified element generation and manipulation.
• Advanced CSS styling capabilities with the styles subpackage.
• Use the StyleManager for advanced CSS features like pseudo-classes, animations, and media queries.

Installation

To install elem, use go get:

go get github.com/chasefleming/elem-go

Usage

Import the elem package in your Go code:

import (
    "github.com/chasefleming/elem-go"
    "github.com/chasefleming/elem-go/attrs"
    "github.com/chasefleming/elem-go/styles"
)

Creating Elements

Here's an example of creating a <div> element with nested <h1>, <h2>, and <p> elements using elem:

content := elem.Div(attrs.Props{
    attrs.ID:    "container",
    attrs.Class: "my-class",
},
    elem.H1(nil, elem.Text("Hello, Elem!")),
    elem.H2(nil, elem.Text("Subheading")),
    elem.P(nil, elem.Text("This is a paragraph.")),
)

When the above Go code is executed and the .Render() method is called, it produces the following HTML:

<div id="container" class="my-class">
    <h1>Hello, Elem!</h1>
    <h2>Subheading</h2>
    <p>This is a paragraph.</p>
</div>

Attributes and Styles

The attrs subpackage provides type-safe attribute functions that ensure you're setting valid attributes for your elements. This helps eliminate potential issues at runtime due to misspelled or unsupported attribute names.

For boolean attributes like checked and selected, you can simply assign them the value "true" or "false". When set to "true", the library will correctly render these attributes without needing an explicit value. For instance:

// Using boolean attributes
checkbox := elem.Input(attrs.Props{
    attrs.Type:    "checkbox",
    attrs.Checked: "true",  // This will render as <input type="checkbox" checked>
})

For setting styles, the styles subpackage enables you to create style objects and convert them to inline CSS strings:

// Define a style
buttonStyle := styles.Props{
    styles.BackgroundColor: "blue",
    styles.Color:           "white",
}

// Convert style to inline CSS and apply it
button := elem.Button(
    attrs.Props{
        attrs.Style: buttonStyle.ToInline(),
    },
    elem.Text("Click Me"),
)

See the complete list of supported attributes in the attrs package, and for a full overview of style properties and information on using the styles subpackage, see the styles README.

Rendering Elements

The .Render() method is used to convert the structured Go elements into HTML strings. This method is essential for generating the final HTML output that can be served to a web browser or integrated into templates.

html := content.Render()

In this example, content refers to an elem element structure. When the .Render() method is called on content, it generates the HTML representation of the constructed elements.

NOTE: When using an element, this method automatically includes a preamble in the rendered HTML, ensuring compliance with modern web standards.

Custom Rendering Options

For more control over the rendering process, such as disabling the HTML preamble, use the RenderWithOptions method. This method accepts a RenderOptions struct, allowing you to specify various rendering preferences.

options := RenderOptions{DisableHtmlPreamble: true}
htmlString := myHtmlElement.RenderWithOptions(options)

This flexibility is particularly useful in scenarios where default rendering behaviors need to be overridden or customized.

Generating Lists of Elements with TransformEach

With elem, you can easily generate lists of elements from slices of data using the TransformEach function. This function abstracts the repetitive task of iterating over a slice and transforming its items into elements.

items := []string{"Item 1", "Item 2", "Item 3"}

liElements := elem.TransformEach(items, func(item string) elem.Node {
    return elem.Li(nil, elem.Text(item))
})

ulElement := elem.Ul(nil, liElements)

In this example, we transformed a slice of strings into a list of li elements and then wrapped them in a ul element.

Conditional Rendering with If

elem provides a utility function If for conditional rendering of elements.

isAdmin := true
adminLink := elem.A(attrs.Props{attrs.Href: "/admin"}, elem.Text("Admin Panel"))
guestLink := elem.A(attrs.Props{attrs.Href: "/login"}, elem.Text("Login"))

content := elem.Div(nil,
    elem.H1(nil, elem.Text("Dashboard")),
    elem.If(isAdmin, adminLink, guestLink),
)

In this example, if isAdmin is true, the Admin Panel link is rendered. Otherwise, the Login link is rendered.

None in Conditional Rendering

elem provides a specialized node None that implements the Node interface but does not produce any visible output. It's particularly useful in scenarios where rendering nothing for a specific condition is required.

showWelcomeMessage := false
welcomeMessage := elem.Div(nil, elem.Text("Welcome to our website!"))

content := elem.Div(nil,
    elem.If[elem.Node](showWelcomeMessage, welcomeMessage, elem.None()),
)

In this example, welcomeMessage is rendered only if showWelcomeMessage is true. If it's false, None is rendered instead, which produces no visible output.

Additionally, None can be used to create an empty element, as in elem.Div(nil, elem.None()), which results in <div></div>. This can be handy for creating placeholders or structuring your HTML document without adding additional content.

Supported Elements

elem provides utility functions for creating HTML elements:

• Document Structure: Html, Head, Body, Title, Link, Meta, Style, Base
• Text Content: H1, H2, H3, H4, H5, H6, P, Blockquote, Pre, Code, I, Br, Hr, Small, Q, Cite, Abbr, Data, Time, Var, Samp, Kbd
• Sectioning & Semantic Layout: Article, Aside, FigCaption, Figure, Footer, Header, Hgroup, Main, Mark, Nav, Section
• Form Elements: Form, Input, Textarea, Button, Select, Optgroup, Option, Label, Fieldset, Legend, Datalist, Meter, Output, Progress
• Interactive Elements: Details, Dialog, Menu, Summary
• Grouping Content: Div, Span, Li, Ul, Ol, Dl, Dt, Dd
• Tables: Table, Tr, Td, Th, TBody, THead, TFoot
• Hyperlinks and Multimedia: Img, Map, Area
• Embedded Content: Audio, Iframe, Source, Video
• Script-supporting Elements: Script, Noscript
• Inline Semantic: A, Strong, Em, Code, I, B, U, Sub, Sup, Ruby, Rt, Rp

Raw HTML Insertion

The Raw function allows for the direct inclusion of raw HTML content within your document structure. This function can be used to insert HTML strings, which will be rendered as part of the final HTML output.

rawHTML := `<div class="custom-html"><p>Custom HTML content</p></div>`
content := elem.Div(nil,
    elem.H1(nil, elem.Text("Welcome to Elem-Go")),
    elem.Raw(rawHTML), // Inserting the raw HTML
    elem.P(nil, elem.Text("More content here...")), 
)

htmlOutput := content.Render()
// Output: <div><h1>Welcome to Elem-Go</h1><div class="custom-html"><p>Custom HTML content</p></div><p>More content here...</p></div>

NOTE: If you are passing HTML from an untrusted source, make sure to sanitize it to prevent potential security risks such as Cross-Site Scripting (XSS) attacks.

HTML Comments

Apart from standard elements, elem-go also allows you to insert HTML comments using the Comment function:

comment := elem.Comment("Section: Main Content Start")
// Generates: <!-- Section: Main Content Start -->

Grouping Elements with Fragment

The Fragment function allows you to group multiple elements together without adding an extra wrapper element to the DOM. This is particularly useful when you want to merge multiple nodes into the same parent element without any additional structure.

nodes := []elem.Node{
    elem.P(nil, elem.Text("1")),
    elem.P(nil, elem.Text("2")),
}

content := elem.Div(nil,
    elem.P(nil, elem.Text("0")),
    elem.Fragment(nodes...),
    elem.P(nil, elem.Text("3")),
)

In this example, the Fragment function is used to insert the nodes into the parent div without introducing any additional wrapper elements. This keeps the HTML output clean and simple.

Handling JSON Strings and Special Characters in Attributes

When using attributes that require JSON strings or special characters (like quotes), make sure to wrap these strings in single quotes. This prevents the library from adding extra quotes around your value. For example:

content := elem.Div(attrs.Props{
    attrs.ID:    "my-div",
    attrs.Class: "special 'class'",
    attrs.Data:  `'{"key": "value"}'`,
}, elem.Text("Content"))

Advanced CSS Styling with StyleManager

For projects requiring advanced CSS styling capabilities, including support for animations, pseudo-classes, and responsive design via media queries, the stylemanager subpackage offers a powerful solution. Integrated seamlessly with elem-go, it allows developers to programmatically create and manage complex CSS styles within the type-safe environment of Go.

Explore the stylemanager subpackage to leverage advanced styling features in your web applications.

HTMX Integration

We provide a subpackage for htmx integration. Read more about htmx integration here.

Examples

For hands-on examples showcasing the usage of elem, you can find sample implementations in the examples/ folder of the repository. Dive into the examples to get a deeper understanding of how to leverage the library in various scenarios.

Check out the examples here.

Tutorials & Guides

Dive deeper into the capabilities of elem and learn best practices through our collection of tutorials and guides:

• Building a Counter App with htmx, Go Fiber, and elem-go
• Building a Go Static Site Generator Using elem-go

Stay tuned for more tutorials and guides in the future!

Contributing

Contributions are welcome! If you have ideas for improvements or new features, please open an issue or submit a pull request.

License

This project is licensed under the MIT License - see the LICENSE file for details.